Longman Dictionary of Contemporary English
n. (context computer technology English) A development status given to a program or application that contains most of the major features, but is not yet complete. Sometimes these versions are released only to a select group of people, or to the general public. The testers are usually expected to report any bugs they encounter or any changes they'd like to see before the final release. This is the second major stage of development following the alpha version, and comes before the release candidate.
Usage examples of "beta version".
It sampled everything, from Chuck Samms' infantile mem- aries of breast-feeding to Nikola Tesla's beta version of the Unified Field Theory to Nameless's still-forming~ first impressions of reality.
It contained the original technical documentation for the beta version of the Ultima Model B.